1. Field of the Invention
The present disclosure relates to a spare-tire installation structure for a vehicle that provides superior impact absorption properties upon collision with minimal addition to vehicle body weight.
2. Description of the Related Art
A spare tire is structurally designed to have at least a predetermined strength to serve as a road tire by taking into account the force applied from a road surface inward or outward in the radial direction of the tire and the environment in which the spare tire may be used.
A typical spare tire, as assembled, has a rubber spare tire body fitted around a metal spare tire wheel.
The spare tire wheel integrally includes a substantially cylindrical drum equipped with the spare tire body and a substantially disk-shaped spoke surface located on the side of the drum that faces the outside of the vehicle when the spare tire is attached to the vehicle for use.
To install the spare tire in a trunk room provided in the rear of the vehicle, for example, the spare tire is accommodated in a spare-tire installation area provided on a floor panel surface in the rear of the vehicle so that the spoke surface lies in a substantially horizontal position.
However, if the spare tire is installed in a substantially horizontal orientation on the floor panel surface in the rear of the vehicle, the radial direction of the tire, in which the tire has relatively high rigidity, corresponds to the longitudinal direction of the vehicle that may also be the direction in which a crushable zone extends.
Because the spare tire and wheel are resistant to fracture or collapse, the spare tire may make it difficult to provide a desired crushable zone for the rear structure of the vehicle. This may degrade impact absorption properties in the event of a rear collision.
Accordingly, examples of known structures include one that allows the spare tire to be rotated so as to tilt frontward or rearward as the rear of the vehicle is deformed upon rear collision (see, for example, Japanese Unexamined Patent Application Publication No. 2006-137329) and one that allows the spare tire to fall toward the bottom of the vehicle without being held between other vehicle components to ensure a desired crushable zone (see, for example, Japanese Unexamined Patent Application Publication No. 2006-290272).
However, the structure that allows a conventional spare tire to be rotated so as to tilt frontward or rearward, and the structure that allows a conventional spare tire to fall toward the bottom of the vehicle without being held between other vehicle components to ensure a desired crushable zone result in a complicated vehicle structure and may, therefore, increase weight and production costs.